From 7a679a3faa381c6a930b08b73b1d4080ad554533 Mon Sep 17 00:00:00 2001
From: Austin Eng <enga@chromium.org>
Date: Thu, 15 Dec 2022 21:15:40 -0800
Subject: [PATCH] Prefix subcase recorder error stacks with the subcase name
 (#2086)

The deferred nature of subcases makes it hard to tell which failures
came from which subcases. Prefix all error messages from subcases with
their subcase name.
---
 src/common/internal/test_group.ts | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/src/common/internal/test_group.ts b/src/common/internal/test_group.ts
index d2846dc602ed..2ad7a7468036 100644
--- a/src/common/internal/test_group.ts
+++ b/src/common/internal/test_group.ts
@@ -525,6 +525,7 @@ class RunCaseSpecific implements RunCase {
             // Make a recorder that will defer all calls until `allPreviousSubcasesFinalizedPromise`
             // resolves. Waiting on `allPreviousSubcasesFinalizedPromise` ensures that
             // logs from all the previous subcases have been flushed before flushing new logs.
+            const subcasePrefix = 'subcase: ' + stringifyPublicParams(subParams);
             const subRec = new Proxy(rec, {
               get: (target, k: keyof TestCaseRecorder) => {
                 const prop = TestCaseRecorder.prototype[k];
@@ -532,6 +533,13 @@ class RunCaseSpecific implements RunCase {
                   testHeartbeatCallback();
                   return function (...args: Parameters<typeof prop>) {
                     void allPreviousSubcasesFinalizedPromise.then(() => {
+                      // Prepend the subcase name to all error messages.
+                      for (const arg of args) {
+                        if (arg instanceof Error) {
+                          arg.message = subcasePrefix + '\n' + arg.message;
+                        }
+                      }
+
                       // eslint-disable-next-line @typescript-eslint/no-explicit-any
                       const rv = (prop as any).apply(target, args);
                       // Because this proxy executes functions in a deferred manner,
@@ -544,8 +552,6 @@ class RunCaseSpecific implements RunCase {
               },
             });
 
-            subRec.info(new Error('subcase: ' + stringifyPublicParams(subParams)));
-
             const params = mergeParams(this.params, subParams);
             const subcaseQuery = new TestQuerySingleCase(
               selfQuery.suite,
@@ -573,6 +579,9 @@ class RunCaseSpecific implements RunCase {
               /* throwSkip */ true,
               getExpectedStatus(subcaseQuery)
             )
+              .then(() => {
+                subRec.info(new Error('OK'));
+              })
               .catch(ex => {
                 if (ex instanceof SkipTestCase) {
                   // Convert SkipTestCase to info messages